Engine installation using machine vision for alignment

ABSTRACT

Installation of an engine to a support structure includes temporarily attaching first and second alignment structures to the support structure and the engine. One of the alignment structures has a target pattern on its surface. The installation further includes using a machine vision system from the other of the mounting structures to indicate the relative position of the target pattern with respect to a reference. The relative position of the target pattern with respect to the reference provides information about relative position of an engine mounting element (e.g., bolt hole) with respect to a corresponding mounting element (e.g., bolt hole) in the support structure. The relative position of the target pattern with respect to the reference can be used to maneuver the engine in order to align the mounting elements.

This is a division of copending U.S. Ser. No. 11/947,767 filed Nov. 29,2007, now U.S. Pat. No. 9,302,785.

BACKGROUND

The Boeing 787 Dreamliner™ airplane has two high bypass turbofanengines, one under each wing. The engines are very large. Each enginehas a length of about 160 inches and a fan diameter of about 110 inches.

The engines are mounted to pylons on the wings. During installation ofan engine, the engine is moved toward a pylon and maneuvered so mountingholes in its mounts are aligned with mounting holes in the pylon. Withthe mounting holes aligned, shear pins are engaged in the engine mounts.Once the shear pins are at full engagement, the engine is moved into itsfinal position and fastened to the pylon with tension bolts.

Maneuvering the engine with respect to the pylon is challenging,especially while lining up the mounting holes for the shear pins.Because the engine is so large and because the mounting holes are at thetop of the engine, visual sight lines to the mounting holes are poor.

SUMMARY

According to an aspect of the present invention, installation of anengine to a support structure includes temporarily attaching first andsecond alignment structures to the support structure and the engine. Oneof the alignment structures has a target pattern on its surface. Theinstallation further includes using a machine vision system from theother of the mounting structures to indicate the relative position ofthe target pattern with respect to a reference. The relative position ofthe target pattern with respect to the reference provides informationabout relative position of an engine mounting element (e.g., a bolthole) with respect to a corresponding mounting element (e.g., a bolthole) of the support structure. The relative position of the targetpattern with respect to the reference can be used to maneuver the enginein order to align the mounting elements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a method in accordance with an embodimentof the present invention.

FIG. 2a is an illustration of an aircraft engine mounted to a pylon.

FIG. 2b is an illustration of an aft engine mount.

FIG. 3 is an illustration of apparatus in accordance with an embodimentof the present invention.

FIG. 4 is an illustration of a method of using the apparatus of FIG. 3to install an aircraft engine.

DETAILED DESCRIPTION

Reference is made to FIG. 1, which illustrates a method of aligning amounting hole of an engine with a corresponding mounting hole of asupport structure. By aligning the mounting holes, a pin, bolt or otherfastener can be inserted through the aligned holes so the engine can besecured to the support structure.

At block 110, a first alignment structure (e.g., a plate) is temporarilyattached to the support structure. Components (e.g., a camera) of amachine vision system are already mounted on the first alignmentstructure. The first alignment structure is attached to a known locationon the support structure. This allows the machine vision system toestablish a reference with respect to a known location on the supportstructure.

Also at block 110, a second alignment structure (e.g., a plate) istemporarily attached to the engine. The second alignment structure maybe attached indirectly (e.g., through an engine mount) or directly tothe engine. The second alignment structure has a target pattern on aportion of its surface. This surface portion will hereinafter bereferred to as the “imaging surface.” The target pattern may include oneor more points, lines, shapes, etc. The target pattern may be painted,etched, printed, silk-screened or otherwise placed on the imagingsurface. The target pattern may even be natural feature (e.g., grains)of the imaging surface.

The second alignment structure is attached to a known location on theengine. This places the target pattern at a known location with respectto the engine.

A relative position of the target pattern with respect to the referencecan be observed. This relative position provides information aboutrelative position of an engine mounting hole with respect to acorresponding mounting hole in the support structure (since thelocations of the reference and the target pattern are known on thesupport structure and the engine).

At block 120, the machine vision system is used to indicate relativeposition of the target pattern with respect to the reference. In someembodiments, the machine vision system performs pattern recognition onthe target pattern, acquiring the target pattern and computing distanceand direction of the target pattern from the reference.

In other embodiments, the machine vision system projects the referenceonto the imaging surface of the second alignment structure. For example,the machine vision system projects laser lines onto the imaging surfaceof the second mounting structure. The machine vision system also createsreal-time images of the imaging surface. The images indicate therelative position of the target pattern with respect to the reference(and, therefore, the relative position of the engine mounting hole withrespect to the corresponding mounting hole in the support structure).The machine vision can also process the images to compute distance anddirection of the target pattern from the reference.

At block 130, the information about the relative position of the targetpattern with respect to the reference is used to maneuver the engine inorder to align the mounting holes. For example, the real-time images aredisplayed to those people maneuvering the engine. In addition toproviding the real-time images, the machine vision system can computedistance/direction commands and make such information available to thosepeople maneuvering the engine.

The engine is continually maneuvered until the target pattern coincideswith or overlaps the reference or reaches some other desired positionwith respect to the reference (the target pattern and reference do notnecessarily have to overlap). Once the target pattern and reference arealigned, the mounting holes are aligned, and the engine is in positionto be secured to the support structure.

In some embodiments, the first alignment structure (temporarily attachedto the support structure) may have the imaging surface (including thetarget pattern), and the second alignment structure (temporarilyattached to the engine) may carry the machine vision components.

The alignment structures may be used to align more than one mountinghole at the same time. An example of aligning multiple holessimultaneously is described below.

The mounting holes are not limited to any particular types of holes. Forinstance, the mounting holes may be tension bolt holes, shear pin holes,etc.

Moreover, a method according to an embodiment of the present inventionis not limited to the alignment of mounting holes. Other types ofmounting elements, such as protrusions (e.g., shear pins), may bealigned with corresponding mounting elements.

A method according to an embodiment of the present invention is notlimited to any particular type of engine. However, the method isespecially useful for installing large aircraft engines and other largeengines where sight lines to mounting holes are poor.

Reference is made to FIG. 2a , which illustrates an aircraft engine 210with forward and aft mounts 220 and 230. The forward and aft mounts 220and 230 are attached to a pylon 240, which is beneath a wing 250.

Additional reference is made to FIG. 2b , which illustrates an exemplaryaft mount 230. The aft mount 230 includes shear pin holes 232 andtension bolt holes 234. The aft mount 230 may be attached to the engine210 using spherical-type ball joints, which are designed to allow theengine 210 to move a little during installation.

Reference is made to FIG. 3, which illustrates apparatus 310 foraligning mounting holes of an aircraft engine with mounting holes of apylon 240. In FIG. 3, only the aft mount 230 of the engine is shown. Theengine is not shown for clarity.

The apparatus 310 includes a lower alignment plate 320 having a targetpattern 330 on an imaging surface 325. The apparatus 310 furtherincludes an upper alignment plate 340 that carries two line-projectinglasers 350 and a camera 360. The alignment plates are shaped to avoidinterferences with surrounding structure, yet provide a clear line ofsight from components 350 and 360 to the imaging surface 325.

The upper alignment plate 340 has shallow indexing pins (not shown) thatcan fit into the mounting holes of the pylon 240. The lower alignmentplate 320 has shallow indexing pins (not shown) that can fit into themounting holes of the aft engine mount 230.

The lower alignment plate 320 allows the target pattern to be indexed tothe mounting holes in the engine. By attaching to the engine mountingholes, the exact spatial relation of the target with respect to theengine mounting holes is known.

The upper alignment plate 340 allows a reference line to be indexed tothe mounting holes in the pylon 240. For example, the reference line isformed by a laser line, or by the line of sight of the camera. Byattaching to the pylon mounting holes, the exact spatial relation of thereference line to the pylon mounting holes is known.

The alignment of the reference line with the target pattern 330 can bedetermined on a test/calibration jig, prior to mounting the alignmentplates 320 and 340. The plates 320 and 340 can be aligned on the jig(e.g., by aligning the indexing pins of the two plates 320 and 340), andthe laser lines can be projected on the imaging surface 325 of the lowerplate 320. The target pattern 330 can be placed on the imaging surface325 at the locations where the laser lines fall on the imaging surface325.

If the machine vision system performs the alternative approach ofpattern recognition, the upper alignment plate 340 will carry the camera360, but not the line-projecting laser. Alignment of the target pattern330 and the reference may be determined by aligning the alignment plates320 and 340 on a test/calibration jig, and using the camera 360 to takea picture of the imaging surface plate of the lower alignment plate 320.Pattern recognition software can use that picture as the target pattern.

Additional reference is made to FIG. 4, which illustrates a method ofinstalling an aircraft engine of a wide body aircraft. At block 410, theupper alignment plate is temporarily attached to the pylon by insertingthe shallow indexing pins of the upper alignment plate into tension boltholes of the pylon. The upper alignment plate may be secured to thepylon using slide block hold-down devices.

Also at block 410, the lower alignment plate is temporarily attached tothe engine by inserting the shallow indexing plugs/pins of the loweralignment plate into tension bolt holes of the aft engine mount. Thesealignment plates will allow shear pins to be partially engaged beforethe plates are removed. The lower alignment plate may be secured to theaft engine mount using thumbscrew bolts that extend through the lowerplate.

At block 420, the engine is moved proximate to an alignment position.For example, the engine may be moved approximately one to two feet awayfrom the alignment position.

The engine may be moved, lifted and subsequently maneuvered by atransporter/loader. An exemplary transporter/loader may include anengine engagement unit (e.g., a pair of coupling assemblies) forengaging an engine, a drive assembly (e.g., a multi-directional drivewheel system) for moving the engine to a desired position on a floorsurface, and a lift assembly (e.g., a pair of scissor lift mechanisms)for raising the engine. The engine can be moved and maneuvered withmultiple (e.g., six) degrees of freedom. A single operator can controlthese assemblies from a control station. An exemplary transporter/loaderis described in U.S. Pat. No. 7,103,952. A transporter/loader thatprovides multi-axis positioning of the engine is available from MaxMovelndustrier AB of Bjurholm, Sweden.

However, movement, positioning and maneuvering of the engine is notlimited to a transporter/loader. For instance, overhead cranes, ormobile lifting devices called “Bootstrap Arms” may be used.

At block 430, the camera begins creating real-time images of the imagingsurface. As the engine is being moved toward the alignment position, thelower alignment plate will appear in the images. Then the target patternwill appear.

At block 440, those images are used to provide information about theposition of the target pattern relative to the reference. The images maybe used by displaying them to the operator in real time. Instead of, orin addition, the images may be processed to generate position/directioncommands, which may be displayed to the operator.

At block 450, the operator uses that information to further maneuver theengine into the alignment position. If the operator is viewing real-timeimages, the operator controls the transporter/loader to maneuver theengine so the target pattern approaches the reference. If commands aredisplayed to the operator, the operator controls the transporter/loaderto maneuver the engine according to those commands.

The operator can change the field of view if additional cameras aremounted to the upper alignment plate. The operator can select differentcameras to monitor different aspects of the installation.

At block 460, after the engine has reached its alignment position (e.g.,the target pattern coincides with the reference), the engagement ofshear pins begins. Both alignment plates are removed once shear pinengagement has begun. The tension bolt holes on the engine mount andpylon are now exposed.

At block 470, after the shear pins have been engaged, the engine ismoved to its final mounting position. The engine mount allows for alittle movement of the engine as the transporter/loader moves the engineagainst the pylon. Then the engine is fastened to the pylon with tensionbolts.

At block 480, the forward mount of the engine is also fastened to thepylon. There is no need to use the alignment apparatus on both enginemounts if the mounting holes of the forward engine mount are alreadylined up with corresponding holes in the pylon.

In some embodiments, the engine can be maneuvered into its finalposition hands-free, without the interaction of a human operator. Thecontrol station may include a closed loop control that receivespositional feedback from the machine vision system. In response to thefeedback, the closed loop control commands the transporter/loader tomaneuver the engine. The method of FIG. 4 may be modified for suchclosed loop control. Commands are still generated at block 440, butthose commands are sent to a closed loop control (instead of beingdisplayed to a human operator) at block 450.

A method according to an embodiment of the present invention helps tostreamline the engine installation process. Continual real-timeinformation is available as to the alignment and positioning of anengine relative to a pylon. Installation is faster and allows for moreaccurate relative positioning of an engine with respect to a pylon.

An operator can remotely view the area of engine interface in real timefrom a “desired perspective” (e.g., looking straight down), in an areawhere it is physically impossible for him to see. In addition, theoperator can change the field of view of the camera to focus on the areaof interest during alignment. These images can be viewed from aconvenient location (e.g., at the control station of thetransporter/loader).

A single operator can move an engine into alignment, thereby eliminatingthe need for spotters and, therefore, problems inherent with spotters.Such problems include erroneous communication with the operator (whichcan result in improper positioning of the engine) and injury to thosespotters in the immediate area of the engine-to-pylon interface.

The invention claimed is:
 1. An apparatus comprising: a pylon having afirst set of mounting holes, the pylon connected to an aircraft wing; anaircraft engine having a second set of mounting holes; a first alignmentplate having a first set of indexing pins removably coupled to the firstset of mounting holes in the pylon, wherein the first alignment platehas an elongated section that extends outwardly from the pylon when thefirst alignment plate is coupled to the set of mounting holes in thepylon; a machine vision system coupled to the elongated section of thefirst alignment plate, the machine vision system configured to generatea reference line at a first spatial relation; and a second alignmentplate having a second set of indexing pins removably coupled to the setof mounting holes in the aircraft engine, wherein the second alignmentplate comprises an elongated first portion coupled to the second set ofindexing pins, an intermediate portion, and an elongated second portion,the elongated first portion connected to a first edge of theintermediate portion to form an approximate 90 degree angle between abottom surface of the elongated first portion and a first side surfaceof the intermediate portion, the elongated second portion connected to asecond edge of the intermediate portion to form an approximate 90 degreeangle between a top surface of the elongated second portion and a secondside surface of the intermediate portion, the elongated second portionextending outwardly from the aircraft engine when the second alignmentplate is coupled to the set of mounting holes in the aircraft engine,wherein the second alignment plate further includes an imaging surfacewith a target pattern at a second spatial relation located on the secondportion, wherein the first and second spatial relations are configuredto align the reference line with the target pattern when the first setof indexing pins is aligned with the second set of indexing pins, andwherein a relative position of the reference line with respect to thetarget pattern is indicative of a relative position of the mountingholes in the pylon with respect to the mounting holes in the aircraftengine with the first set of indexing pins coupled to the mounting holesin the pylon and the second of indexing pins coupled to the mountingholes in the aircraft engine; wherein the machine vision system includesa camera configured to generate images of the imaging surface showingthe relative position of the reference line with respect to the targetpattern.
 2. The apparatus of claim 1, wherein the machine vision systemincludes a laser system capable of projecting the reference line ontothe imaging surface.
 3. The apparatus of claim 1, wherein the camera isconfigured to capture and store a reference picture of the imagingsurface with the target pattern at an alignment position, and themachine vision system is capable of performing a pattern matching tofind the reference picture in the images.
 4. The apparatus of claim 1,further comprising a transporter/loader capable of maneuvering theaircraft engine to align the set of mounting holes in the aircraftengine with the set of mounting holes in the pylon.
 5. The apparatus ofclaim 1, wherein one of the approximate 90 degree angles comprises a 90degree angle.
 6. The apparatus of claim 1, wherein the reference line isa picture of the imaging surface with the target pattern at an alignmentposition, and wherein the machine vision system is configured to performpattern matching to match one of the images with the picture.
 7. Theapparatus of claim 1, wherein the first and second sets of mountingholes comprise shear pin holes.
 8. The apparatus of claim 1, wherein thefirst alignment plate comprises an upper alignment pate and the secondalignment plate comprises a lower alignment plate.
 9. The apparatus ofclaim 1, wherein the camera is capable of generating real-time images ofthe imaging surface.
 10. An apparatus comprising: a pylon having a firstset of mounting holes, the pylon connected to an aircraft wing; anaircraft engine having a second set of mounting holes; a first alignmentplate having a first set of indexing pins removably coupled to the firstset of mounting holes in the pylon, wherein the first alignment platehas an elongated section that extends outwardly from the pylon when thefirst alignment plate is coupled to the set of mounting holes in thepylon; a machine vision system coupled to the elongated section of thefirst alignment plate, the machine vision system comprising a lasersystem for projecting a reference line at a first spatial relation; anda second alignment plate having a second set of indexing pins removablycoupled to the set of mounting holes in the aircraft engine, wherein thesecond alignment plate comprises an elongated first portion coupled tothe second set of indexing pins, an intermediate portion, and anelongated second portion, the elongated first portion connected to afirst edge of the intermediate portion to form an approximate 90 degreeangle between a bottom surface of the elongated first portion and afirst side surface of the intermediate portion, the elongated secondportion connected to a second edge of the intermediate portion to forman approximate 90 degree angle between a top surface of the elongatedsecond portion and a second side surface of the intermediate portion,the elongated second portion extending outwardly from the aircraftengine when the second alignment plate is coupled to the set of mountingholes in the aircraft engine, wherein the second alignment plate furtherincludes an imaging surface with a target pattern at a second spatialrelation located on the second portion, wherein the first and secondspatial relations are configured to align the reference line with thetarget pattern when the first set of indexing pins is aligned with thesecond set of indexing pins, and wherein a relative position of thereference line with respect to the target pattern is indicative of arelative position of the mounting holes in the pylon with respect to themounting holes in the aircraft engine with the first set of indexingpins coupled to the mounting holes in the pylon and the second ofindexing pins coupled to the mounting holes in the aircraft engine;wherein the machine vision system includes a camera configured togenerate images of the imaging surface showing the relative position ofthe reference line with respect to the target pattern, and wherein thecamera is configured to capture and store a reference picture of theimaging surface with the target pattern at an alignment position, andthe machine vision system is capable of performing a pattern matching tofind the reference picture in the images.
 11. The apparatus of claim 10,wherein one of the approximate 90 degree angles comprises a 90 degreeangle.
 12. The apparatus of claim 10, wherein the first and second setsof mounting holes comprise shear pin holes.
 13. The apparatus of claim10, wherein the first alignment plate comprises an upper alignment pateand the second alignment plate comprises a lower alignment plate. 14.The apparatus of claim 10, further comprising a transporter/loadercapable of maneuvering the aircraft engine to align the set of mountingholes in the aircraft engine with the set of mounting holes in thepylon.
 15. An apparatus comprising: a pylon having a first set ofmounting holes, the pylon connected to an aircraft wing; an aircraftengine having a second set of mounting holes; a first alignment platehaving a first set of indexing pins removably coupled to the first setof mounting holes in the pylon, wherein the first alignment plate has anelongated section that extends outwardly from the pylon when the firstalignment plate is coupled to the set of mounting holes in the pylon; amachine vision system coupled to the elongated section of the firstalignment plate, the machine vision system comprising a laser system forprojecting a reference line at a first spatial relation; and a secondalignment plate having a second set of indexing pins removably coupledto the set of mounting holes in the aircraft engine, wherein the secondalignment plate comprises an elongated first portion coupled to thesecond set of indexing pins, an intermediate portion, and an elongatedsecond portion, the elongated first portion connected to a first edge ofthe intermediate portion to form an approximate 90 degree angle betweena bottom surface of the elongated first portion and a first side surfaceof the intermediate portion, the elongated second portion connected to asecond edge of the intermediate portion to form an approximate 90 degreeangle between a top surface of the elongated second portion and a secondside surface of the intermediate portion, the elongated second portionextending outwardly from the aircraft engine when the second alignmentplate is coupled to the set of mounting holes in the aircraft engine,wherein the second alignment plate further includes an imaging surfacewith a target pattern at a second spatial relation located on the secondportion, wherein the first and second spatial relations are configuredto align the reference line with the target pattern when the first setof indexing pins is aligned with the second set of indexing pins, andwherein a relative position of the reference line with respect to thetarget pattern is indicative of a relative position of the mountingholes in the pylon with respect to the mounting holes in the aircraftengine with the first set of indexing pins coupled to the mounting holesin the pylon and the second of indexing pins coupled to the mountingholes in the aircraft engine; wherein the machine vision system includesa camera configured to generate real-time images of the imaging surfaceshowing the relative position of the reference line with respect to thetarget pattern.
 16. The apparatus of claim 15, wherein one of theapproximate 90 degree angles comprises a 90 degree angle.
 17. Theapparatus of claim 15, wherein the camera is configured to capture andstore a reference picture of the imaging surface with the target patternat an alignment position, and the machine vision system is capable ofperforming a pattern matching to find the reference picture in theimages.
 18. The apparatus of claim 15, wherein the first and second setsof mounting holes comprise shear pin holes.
 19. The apparatus of claim15, wherein the first alignment plate comprises an upper alignment pateand the second alignment plate comprises a lower alignment plate. 20.The apparatus of claim 15, further comprising a transporferlloadercapable of maneuvering the aircraft engine to align the set of mountingholes in the aircraft engine with the set of mounting holes in thepylon.